1. Field of the Invention
The present invention relates to a clarifying device for use in an aquarium.
2. Description of the Related Art
As a clarifying device for use in an aquarium, a bottom-dispose-type clarifying device which is disposed on a bottom of an aquarium, an upper-dispose-type clarifying device which is disposed on an upper part of an aquarium, and an outer-dispose-type clarifying device which is disposed on an outer surface of a wall of an aquarium, are known. In conventional clarifying devices, clarifying materials are fixedly disposed therein to biochemically clarify water in an aquarium.
In a conventional clarifying device, however, since water in an aquarium is biochemically purified when passed through clarifying materials fixedly accommodated in the device, the water does not sufficiently contact the clarifying materials, resulting in low clarifying efficiency.
In a conventional bottom-dispose-type clarifying device, the device often clogs, which causes an insufficient water clarification. This requires a replacement of the clarifying materials in a relatively short period.
A timing for changing clarifying materials is generally decided by a decreased degree of flow amount of the clarified water passing through the clarifying device. However, the user's memory of an initial water flow amount, which is a water flow amount passing through newly placed clarifying materials, becomes vague as time passes after the replacement of the clarifying materials. Therefore, it is not easy to compare the decreased water flow amount with the initial water flow amount. As a result, it is difficult to find a correct timing for changing the clarifying materials.